Make `<servicename>::Client` `Clone + Debug` (#330)

* failed: add Debug trait to Client

* fix: KTLint fixes

* feat: derive Clone for Client

* feat: custom impl Debug for Config

* fix: revert the Debug derives inside Config

* doc: add comment explain why we do custom impl Debug for Config

Co-authored-by: Shing Lyu <shinglyu@amazon.nl>
Co-authored-by: Russell Cohen <rcoh@amazon.com>